Implement hasMetaParents and getMetaParents interop API

Fixes #401

Author: msimacek

graalpython/com.oracle.graal.python.test.integration/src/com/oracle/graal/python/test/integration/interop/JavaInteropTest.java

@@ -789,6 +789,35 @@ def foo(obj):
             Value result = foo.execute(recursiveList);
             assertEquals(result.as(String.class), "[1, [...]]");
         }
+
+        @Test
+        public void testMetaParents() throws IOException {
+            Source source = Source.newBuilder("python", """
+                            class Foo:
+                                pass
+                            class Bar(Foo):
+                                pass
+                            Bar
+                            """, "input").build();
+            Value bar = context.eval(source);
+            assertTrue(bar.isMetaObject());
+            assertEquals(bar.getMetaSimpleName(), "Bar");
+            assertTrue(bar.hasMetaParents());
+            Value barParents = bar.getMetaParents();
+            assertTrue(barParents.hasArrayElements());
+            assertEquals(barParents.getArraySize(), 1);
+            Value foo = barParents.getArrayElement(0);
+            assertTrue(foo.isMetaObject());
+            assertEquals(foo.getMetaSimpleName(), "Foo");
+            assertTrue(foo.hasMetaParents());
+            Value fooParents = foo.getMetaParents();
+            assertTrue(fooParents.hasArrayElements());
+            assertEquals(fooParents.getArraySize(), 1);
+            Value object = fooParents.getArrayElement(0);
+            assertTrue(object.isMetaObject());
+            assertEquals(object.getMetaSimpleName(), "object");
+            assertFalse(object.hasMetaParents());
+        }
     }
 
     @RunWith(Parameterized.class)

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/objects/PythonAbstractObject.java

@@ -149,6 +149,7 @@
 import com.oracle.graal.python.runtime.PythonContext;
 import com.oracle.graal.python.runtime.PythonOptions;
 import com.oracle.graal.python.runtime.exception.PException;
+import com.oracle.graal.python.runtime.object.PythonObjectFactory;
 import com.oracle.graal.python.runtime.sequence.storage.SequenceStorage;
 import com.oracle.graal.python.util.OverflowException;
 import com.oracle.graal.python.util.PythonUtils;
@@ -1498,6 +1499,41 @@ public Object getMetaObject(
         }
     }
 
+    @ExportMessage
+    public boolean hasMetaParents(
+                    @Bind("$node") Node inliningTarget,
+                    @Exclusive @Cached TypeNodes.IsTypeNode isTypeNode,
+                    @Exclusive @Cached TypeNodes.GetBaseClassesNode getBaseClassNode,
+                    @Exclusive @Cached GilNode gil) {
+        boolean mustRelease = gil.acquire();
+        try {
+            return isTypeNode.execute(inliningTarget, this) && getBaseClassNode.execute(inliningTarget, this).length > 0;
+        } finally {
+            gil.release(mustRelease);
+        }
+    }
+
+    @ExportMessage
+    public Object getMetaParents(
+                    @Bind("$node") Node inliningTarget,
+                    @Exclusive @Cached PythonObjectFactory factory,
+                    @Exclusive @Cached TypeNodes.IsTypeNode isTypeNode,
+                    @Exclusive @Cached TypeNodes.GetBaseClassesNode getBaseClassNode,
+                    @Exclusive @Cached GilNode gil) throws UnsupportedMessageException {
+        boolean mustRelease = gil.acquire();
+        try {
+            if (isTypeNode.execute(inliningTarget, this)) {
+                var bases = getBaseClassNode.execute(inliningTarget, this);
+                if (bases.length > 0) {
+                    return factory.createTuple(bases);
+                }
+            }
+            throw UnsupportedMessageException.create();
+        } finally {
+            gil.release(mustRelease);
+        }
+    }
+
     @ExportMessage
     public int identityHashCode(
                     @Bind("$node") Node inliningTarget,